Foundry sand compositions

ABSTRACT

A FOUNDRY MOLD AND CORE SAND COMPOSITION IS PROVIDED MADE UP OF CHROMITE SAND, CHROMITE SAND FLOUR, BENTONITE, CEREAL BINDER AND WATER WHICH COMPOSITION MAY BE STORED FOR EXTENDED PERIODS OF TIME IN THE MIXED CONDITION WITHOUT DETERIORATION AND WHICH MAY BE USED FOR PATCHING, FOR THE FORMATION OF INTRICATE MOLDS AND CORES AND FOR ANY OTHER USE TO WHICH FOUNDRY SAND COMPOSITION ARE CONVENTIONALLY USED.

3,552,983 FOUNDRY SAND COMPOSITIONS John V. Phillips, 248 Voss Road,

Bethel Park, Pa. 15102 No Drawing. Filed July 30, 1969, Ser. No. 846,288 Int. Cl. B28b 7/34 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to foundry sand compositions and particularly to a water base sand molding composition which may be stored and yet will dry rapidly when used and exposed to the air.

The problems of finding a sand composition for foundry use which will take intricate shapes, can be stored wet, and yet can be rammed and oven dried to get clean casting without expensive chip-ping are problems which have been the object of considerable research in the foundry industry for many years. There have, over the years, been developed many binders and sand formulations for making cores and molds. Historically, molds and cores are formed by mixing sands of various types and binders and drying same principally by using large heated, drying furnaces. This practice is time consuming and expensive. There have been more recently developed a variety of binders which can be used with sands to eliminate the use of the heating furnaces for drying and the resulting cores and molds can be air dryed to produce a satisfactory resultant core or mold. These materials are based on resinous primers such as urea furfuryl alcohol formaldehyde and the like materials. They depend upon a polymerization reaction for their usefulness. Once mixed, they have a very short storage life, and

they are subject to many problems in use. There has long -The present invention provides just such a foundry composition.

I have developed a foundry sand composition which is water based and does not use any of the polymerizable drying oils as a binder. It may be premixed and stored for a week or more under proper conditions. The core or mold when dryed, is extremely hard making it easy to handle, and because of its quality, intricate shapes can be made at a minimum thickness While core breakage is kept to a minimum.

I provide a foundry sand composition which in its broadest range has the following makeup:

About 150 lbs-225 lbs. of Chromite Sand (A.F.A. Grain Fineness No. 80)

About 75 lbs.l50 lbs. Chromite Sand Flour (A.F.A. Grain Fineness No. 325) About 3 lbs.5 lbs. of Western Bentonite About /2 lbs.2 lbs. of Corn Cereal Binder The foregoing composition is mixed with sufficient moisture to provide a handleable and formable mix- United States Patent 0 3,552,983 Patented Jan. 5, 1971 ture. This will amount to about 2 /2 gallons of Water in the above amount of sand composition. While the foregoing broad general range of material will produce the desired results, I prefer the following narrower composition.

200 lbs. Chromite Sand (A.F.A. Grain Fineness No.

lbs. Chromite Sand Flour (A.F.A. Grain Fineness No. 325) 3 /2 lbs. (2 qt.) Western Bentonite 1 lb (1 qt.) Mogul. (Corn Cereal Binder) to which is added sufiicient water to make the mixture formable. The preferred amount is about 2 /2 gallons. The mixture is mulled for about 2% minutes and formed into the desired cores and molds. The product resulting from the foregoing narrow composition will have the following grain fineness.

GRAIN FINENESS The general physical characteristics of the composition are:

Sand Analysis Moisture5.5-6.0% Green compression8.5-9.0 p.s.i. Green permeability810 Dry shear73 plus (p.s.i.) Grain fineness number--l75 average) 2" specimen-320 grams Compositions made according to the above described mixture when mulled with water only, have been packaged in polyethylene bags and stored for as much as seven weeks with test cores being made everyday with the production of very satisfactory cores even on the seventh. week with no indicated deterioration in the mixture.

The composition of this invention can be used throughout the foundry in any troublesome areas of molds or cores with the elimination of conventional oil binders and oil sand compositions. The mixture is particularly advantageous in patching damaged core or mold sections. For example, a core which has had a portion broken away may be patched by applying a light coat of good grade ceramic base core paste (Water soluble) to the damaged area and drying it until tacky. The composition of the present invention is then applied and rammed firmly. The patched area is then permitted to dry. The resulting patched core will show no parting line at the patched area. The composition is very useful for patching lift hook holes on the metal face of cores and for the variety of other purposes which had heretofore been very difficult to handle. The composition of this invention can 'be dried at any normal oven temperature from 375 F. and up. However, as has ben pointed out, it will air dry rapidly on small patched areas and can be used as patching on any of the conventional foundry sand core oil compositions. The range of compositions which I have set out in this particular application is one which defines a composition highly useful for solving problem areas in forming molds and cores. The outside limits are critical. If the composition is altered outside the limits her'e disclosed, the composition becomes too brittle'om the'one hand and on the other hand; there tonite, about /z2 lbs. of Cereal Binder, and sufficient water to make a forma'ble mixture;

I 2. A composition for foundry sand cores and iiiolds as claimed in claim 1 wherein theCerealB inder is Corn Cereal Binder. l

, 3. A composition as claimed in claim" 1 wherein there is provided 200 lbs. of Chromite Sand, 100lbs. of Chromite Sand Flour, 3 /2 lbs. of Bentonite, 1 /2 lbsjof Corn which may be'formed and set. a e

Cereal Binder, and s-ufficient water to form a mixtnre 4. A composition as claimed in claim 1 wherein the Chromite Sand has a grain fineness in the A.F.A. of 80,

and the Chromite Sand Flour, has a grain fineness A.F.A.

I :ReferencesCited UNITED STATES PATENTS v 2,504,133 4/1950 Kerlin. 10638.5X 2,790,218 4/ 1957 Kohl et a1. 10'6-38.35X 2,798,817 7/1957 Lund 10638.23 2,830,913 4/1958 Meyers et a1. l06--38.9 3,146,113" 

